1. Field of the Invention
The present invention relates to an improvement in an automatic choke system for a carburetor, comprising: a wax-type temperature sensing section attached to an engine; and an output section providing a connection between the temperature sensing section and a choke valve of the carburetor, and operated to open the choke valve in response to heat receiving operation of the temperature sensing section.
2. Description of the Related Art
Such an automatic choke system for a carburetor is known, for example, as disclosed in Japanese Utility Model Laid-Open No. 57-182241.
In the conventional automatic choke system for a carburetor, a wax-type temperature sensing section has a cylinder, a piston slidably supported in the cylinder and having one end projecting out of the cylinder, wax contained in the movable cylinder and causing the movable cylinder and the stationary piston to move relative to each other in the axial direction when it is thermally expanded, and a return spring urging the movable cylinder and the stationary piston in the direction to compress the wax. The cylinder is mounted on the engine with the wax facing a high-temperature portion of the engine, and the piston is connected to the output section. In this automatic choke system, the wax is always exposed to the high-temperature portion of the engine, so that the rate at which heat is received from the engine is constant, and thus the rate of opening the choke valve is also constant with the progress of engine warming-up operation.
However, in order to appropriately perform the engine warming-up operation, it is required to increase the rate of opening the choke valve immediately after a start of engine warming-up operation and to decrease it as approaching the completion of warming-up operation.